In the eight days and 100 miles we’ve been hiking, we’ve come across naturally-occurring water out here twice. All anyone thinks about when planning the next segment of their hike is water: where it is, how sure they can be of it, and how hot and far it is between here and there. It is, by far, the dominant factor in our hike so far — and probably will be for the next 600 miles, too.

(Isn’t it crazy to say the next 600 miles about anything you do? It’s so ridiculous, it makes me laugh whenever I find myself saying it.)

Water is such a critical consideration that someone — there are a lot of benevolent “someone”s out here on the PCT, invisible helping hands all over the place — runs the PCT Water Report, a website that compiles reports sent in by hikers all up and down the trail. This turns into a Google spreadsheet that I’ve got on my phone, refreshing at every opportunity, and it’s how we can set out, feeling confident that the spring 18.1 miles ahead from where we woke up this morning would be flowing and give us plenty to drink. And it’s how we could know that the water cache about halfway in between here and there was also well stocked, and something we could count on.

What’s a water cache, you ask? It’s any place where a trail angel (more benevolent, invisible helping hands) leaves water out on or near the trail so that hikers can take some. They typically take the form of a milk crate full of gallon jugs of water — and, this year, typically empty jugs. Partly due to the drought, but mostly because there are so many people hiking the PCT this year (over 2,000 permits were issued, something like double last year), water caches get used up fast, and the rule is: never, ever count on water caches — always assume you’ll get there and they’ll be dry.

The “Third Gate Water Cache”, however, which we came across (and filled our water from) today, is a different story. This one is truly massive: I counted 240 one-gallon jugs of water, all in cardboard boxes, set out neatly underneath tarps…all basically in the middle of the desert. You get there and there are signs telling you which ones to use first, what to do with empty jugs, how to dispose of no-longer-needed cardboard boxes…it’s amazing, really. We did some rough math and figured this was probably enough water for 400 hikers. And somebody brings this all in, in their truck, down a long, dusty dirt road, every week! It’s incredibly impressive — and incredibly useful.

Why? Well, as it turns out, water weighs a lot. Two-point-two pounds per liter, in fact. And, out here, on dry stretches, you can easily end up carrying six or seven liters — my maximum capacity is eight and a half, and I’ve carried that much (once). That’s nearly nineteen pounds, in water alone! Believe me, when you try to hoist your pack after filling it with that much water, it’s something close to terrifying. Being able to count on an additional water source, and thus being able to carry less water, makes a huge, huge difference.

Every morning, and after every water stop during the day, we carefully calculate how far it will be to the next water stop, look up at the skies to see how sunny and hot it’ll be, look at the elevation profile to see how much climbing we’ll be doing, and fill up our water accordingly. We’re conservative, of course — we almost always get there with more than enough to spare, and never once have we even come close to running out. Still, water dominates planning out here in the desert almost completely, and I fully expect it will for many weeks to come.

In other news: today we hiked our longest day so far — 18.1 miles — and hit mile 100 of the PCT! It’s kind of crazy that that’s less than four percent of the entire trail, but also kind of cool. Even as the entire thing seems ludicrously long, it’s nice to have a marker — a first box of achievement to check.